The present invention relates, in general, to fluid fittings and, more particularly, the instant invention relates to LOKRING(copyright) fittings.
Various types of fittings have been developed for joining tubes and pipes to other tubes and pipes, or to fluid apparatus such as pumps, fluid motors, and actuation cylinders. For thin walled tubing or pipe, various types of fittings are used which compress against the outside diameter of the tube or pipe to create a seal. One particular type of fitting includes a swage ring which is forced over the fitting to compress it radially inward against the tube or pipe. Generally, this type of fitting has one or more circumferential ridges on its I.D. which, when compressed inwardly by the swage ring, engage the O.D. of the tube or pipe to create one or more circumferential seals.
An example of such a fitting is provided by U.S. Pat. No. 5,114,191 PIPE FITTING WITH COUPLING BODY AND IMPROVED ISOLATION TOOTH ARRANGEMENT. This fitting provides a plurality of circumferential ridges, which are referred to as teeth, on the I.D. of the fitting. When the fitting is compressed inwardly by a swage ring, the circumferential teeth engage the O.D. of the pipe to provide seals. This particular fitting, furthermore, has an isolation tooth at an outboard location of the fitting. The isolation tooth serves to protect the seals from bending loads on the pipe.
The isolation tooth in this patent consists of a plurality of isolation gripping teeth separated by isolation tooth grooves. The isolation gripping teeth and the isolation tooth grooves appear to run circumferentially about the I.D. of the fitting.
The isolation tooth arrangement in this patent appears to have some merit for protecting the seals from bending moments, but inasmuch as the isolation gripping teeth run circumferentially, they are not believed to be particularly suitable for resisting torsion about the axis of the pipe.
The type of tool employed for assembling the fitting to the tube or pipe is described in U.S. Pat. No. 5,305,510.
The teachings of the copending application cited above and the issued U.S. Pat. Nos. 5,114,191 and 5,305,510 are hereby incorporated into the present application by reference thereto.
In one aspect, the present invention is a fitting for a fluid pressure conduit. The fitting includes a coupling body having a substantially axisymmetrical inside surface, the inside surface engaging an outside surface of the fluid pressure conduit. The inside surface has at least one substantially axisymmetrical seal formed as at least one axisymmetrical ridge on the inside surface of the coupling body. There is at least one seal land on an outside surface of the coupling body adjacent the substantially axisymmetrical seal(s). There are a plurality of anti-torsion ridges on the inside surface of the coupling body, the anti-torsion ridges having friction surfaces for resisting torsion between the fitting and the fluid pressure conduit. Furthermore, there is at least one torsion land formed on the outside surface of the coupling body adjacent the torsion ridges. The fitting also includes a ring for fitting over the coupling body, the ring engaging the at least one seal land to force the seal(s) into engagement with the outside surface of the fluid conduit, the ring further engaging the torsion land(s) to force the plurality of anti-torsion ridges into engagement with the fluid pressure conduit.
In another aspect, the invention is a fluid pressure device which has a housing for containing a fluid. A fitting is either formed integrally with or attached to the housing. The fitting enables attachment of a fluid pressure conduit. The fitting includes a coupling body having a substantially axisymmetrical inside surface for engaging an outside surface of the fluid pressure conduit. There is at least one substantially axisymmetrical seal formed as at least one axisymmetrical ridge on the inside surface of the coupling body and at least one seal land on an outside surface of the coupling body adjacent the substantially axisymmetrical seal(s). There are a plurality of anti-torsion ridges on the inside surface of the coupling body, the anti-torsion ridges having friction surfaces for resisting torsion between the fitting and the fluid pressure conduit. There is also at least one torsion land formed on the outside surface of the coupling body adjacent the at least one torsion ridge. The fitting includes a ring for fitting over the coupling body, the ring engaging the seal land(s)s to force the seal(s) into engagement with the outside surface of the fluid conduit, the ring further engaging the torsion land(s) to force the plurality of anti-torsion ridges into engagement with the fluid pressure conduit.
In another aspect, the invention is a coupling for joining a first fluid pressure conduit to a second fluid pressure conduit, the coupling including a first fitting and a second fitting in back to back relationship. The first fitting and the second fitting are either formed integrally with one another or attached to one another, the second fitting being substantially identical to the first fitting. The first fitting includes a coupling body having a substantially axisymmetrical inside surface, the inside surface engaging an outside surface of the first fluid pressure conduit. There is at least one substantially axisymmetrical seal formed as one or more axisymmetrical ridges on the inside surface of the coupling body. There is also at least one seal land on an outside surface of the coupling body adjacent the substantially axisymmetrical seal(s). The coupling body also has a plurality of anti-torsion ridges on the inside surface, the anti-torsion ridges having friction surfaces for resisting torsion between the fitting and the first fluid pressure conduit. Furthermore, there is at least one torsion land formed on the outside surface of the coupling body adjacent the torsion ridges. The coupling also includes a ring for fitting over the coupling body, the ring engaging the seal land(s) to force the seal(s) into engagement with the outside surface of the first fluid conduit. The ring further engages the torsion land(s) to force the plurality of anti-torsion ridges into engagement with the first fluid pressure conduit.
It is therefore one of the primary objects of the present invention to provide a fluid fitting having improved torsion capabilities.
Another object of the present invention is to provide a fluid fitting for a pipe or tube having improved torsion resistance.
Still another object of the present invention is to provide a fluid fitting for thin walled tubing which resists rotation due to torsion.
Yet another object of the present invention is to provide a fluid fitting having a plurality of anti-torsion ridges to resist rotation of the tube or pipe within the fitting.
Yet another object of the present invention is to provide a fluid fitting having a plurality of anti-torsion ridges having non axisymmetrical gripping surfaces.
Still another object of the present invention is to provide a fluid fitting having a plurality of anti-torsion ridges which do not interfere with one another.
A further object of the present invention is to provide a fluid fitting for thin walled tubing which has anti-torsion ridges which have minimal tendency to reduce the I.D. of the tubing.
It is yet another object of the present invention to provide an embodiment of a fluid fitting for tubing or pipe which has anti-torsion ridges having knurled surfaces to improve torsion resistance.
An additional object of the present invention is to provide an embodiment of a fluid fitting for tubing or pipe which has anti-torsion ridges having broached surfaces to improve torsion resistance.
It is an additional object of the present invention to provide a fluid fitting for joining two tubes or pipes, the fitting resisting torsion about the axis of the two tubes or pipes.
In addition to the various objects and advantages of the present invention which have been generally described above, there will be various other objects and advantages of the invention that will become more readily apparent to those persons who are skilled in the relevant art from the following more detailed description of the invention, particularly, when the detailed description is taken in conjunction with the attached drawing figures and with the appended claims.